In the past, devices have been known in which the drowsiness of a driver of a vehicle is detected, and issues a warning to the driver when drowsiness is detected. For example, Japanese Unexamined Patent Application Publication No. 2009-28237 discloses a device that estimates the drowsiness of a driver on the basis of the position of an eyelid detected from a face image of a driver of a vehicle. In addition, Japanese Unexamined Patent Application Publication No. 2007-213377 discloses a device that detects feature points of the upper and lower eyelids from a face image by image processing.